Zoom lens and imaging apparatus

ABSTRACT

A zoom lens includes first, second, third, and fourth lens groups respectively having positive, negative, negative, and positive powers. The first lens group includes an 11 lens group having a negative power, which is fixed while focusing, a 12 lens group having a positive power, which moves while focusing, and a 13 lens group having a positive power, which is fixed while focusing. The 12 lens group includes a positive lens having a surface having a radius of curvature with a smaller absolute value toward the image side; and a cemented lens constituted by a negative lens toward the object side and a positive lens toward the image side, cemented together at a joint surface having a convex surface toward the object side. The focal distance f12 of the 12 lens group and the focal length fw of the entire system at the wide angle end satisfy the relationship: 
       3.0&lt; f 12/ fw &lt;20.0.

TECHNICAL FIELD

The present invention is related to a zoom lens. Particularly, thepresent invention is related to a zoom lens which can be favorablyemployed in imaging apparatuses such as electronic cameras.

In addition, the present invention is related to an imaging apparatusequipped with such a zoom lens.

RELATED ART

Zoom lenses are often mounted on imaging apparatuses, such as digitalcameras, digital cinema cameras, video cameras, broadcast cameras, andsurveillance cameras. Among such imaging apparatuses, there isparticular demand for broadcast cameras and digital cinema cameras tohave wide angles of view and to suppress variations in angles of viewduring focusing operations. Various zoom lenses have been conventionallyproposed in order to meet this demand.

For example, Japanese Unexamined Patent Publication Nos. 6(1994)-242378,9(1997)-015501, 10(1998)-062686, and Japanese Patent Publication No. 59(1984)-004686 disclose zoom lenses in which a first group lens isdivided into an 11 lens group having a negative refractive power, a 12lens group having a positive refractive power, and a 13 lens grouphaving a positive refractive power. These zoom lenses are configuredsuch that focusing operations are performed by moving only the 12 lensgroup.

DISCLOSURE OF THE INVENTION

However, the objectives of the conventional zoom lenses disclosed inJapanese Unexamined Patent Publication Nos. 6(1994)-242378,9(1997)-015501, and 10 (1998)-062686 are to achieve high variablemagnification ratios. It cannot be said that the first lens group ofthese zoom lenses are sufficiently miniaturized, although image sizes tobe imaged are not particularly large. Recently, there has been aparticular increase in demand for portable broadcast lenses. Therefore,compact and light weight zoom lenses having large image sizes aredesired. However, the aforementioned conventional lenses cannotsufficiently meet this demand.

Although neither the angle of view nor the F number are described forthe conventional zoom lens disclosed in Japanese Patent Publication No.59 (1984)-004686, it cannot be said that this zoom lens has asufficiently wide angle of view, taking the examples of numerical valuesthereof into consideration.

The present invention has been developed in view of the foregoingcircumstances. It is an object of the present invention to provide azoom lens having a wide angle of view that can suppress variations inangles of view while changing magnification, and further achievessufficient reductions in size and weight, as well as high performance.

A zoom lens of the present invention substantially consists of:

a first lens group having a positive refractive power, which is fixedwhile changing magnification;

a second lens group having a negative refractive power, which moves froman object side to an image side while changing magnification from a wideangle end to a telephoto end;

a third lens group having a negative refractive power, which correctsmovement of an imaging surface while changing magnification; and

a fourth lens group having a positive refractive power, which is fixedwhile changing magnification, provided in this order from the objectside;

the first lens group substantially consisting of: an 11 lens grouphaving a negative refractive power, which is fixed during focusingoperations; a 12 lens group having a positive refractive power, whichmoves during focusing operations; and a 13 lens group having a positiverefractive power, which is fixed during focusing operations, provided inthis order from the object side;

the 12 lens group substantially consisting of: a positive lens (a lenshaving a positive refractive power) having a surface having a radius ofcurvature with a smaller absolute value toward the image side; and acemented lens constituted by a negative lens (a lens having a negativerefractive power) toward the object side and a positive lens toward theimage side, cemented together at a joint surface having a convex surfacetoward the object side, provided in this order from the magnificationside;

the 12 lens group satisfying the following conditional formula:

3.0<f12/fw<20.0  (1)

wherein f12 is the focal length of the 12 lens group, and fw is thefocal length of the entire system at the wide angle end.

Note the expression “substantially consists of . . . ” stated threetimes above means that the zoom lens may lens may also include othercomponents, such as lenses that practically do not have any power,optical elements other than lenses such as aperture stops and coverglass, and mechanical components such as lens flanges, a lens barrel, animaging device, and a blur correcting mechanism.

In addition, the surface shapes and the signs of refractive powers ofthe lenses of the zoom lens of the present invention will be those inthe paraxial regions for lenses that include aspherical surfaces.

It is particularly desirable for the zoom lens of the present inventionto satisfy the following conditional formula within the range defined byConditional Formula (1).

4.0<f12/fw<10.0  (1)′

It is desirable for the zoom lens of the present invention to satisfythe following conditional formula:

−5.0<f11/fw<−0.5  (2)

wherein f11 is the focal length of the 11 lens group, and fw is thefocal length of the entire system at the wide angle end.

Further, it is particularly desirable for the following conditionalformula to be satisfied within the range defined by Conditional Formula(2).

−3.0<f11/fw<−1.2  (2)′

In the zoom lens of the present invention, it is desirable for the 11lens group to substantially consist of: a negative meniscus lens havinga concave surface toward the image side; a negative meniscus lens havinga concave surface toward the image side; and a cemented lens constitutedby a biconcave lens toward the object side and a biconvex lens towardthe image side which are cemented together, provided in this order fromthe object side (hereinafter, referred to as the basic configuration ofthe 11 lens group).

In the case that the 11 lens group of the zoom lens of the presentinvention has the basic configuration described above, it is desirablefor following conditional formula to be satisfied:

0.60<D4/f1<2.0  (3)

wherein D4 is the distance (a spatial distance along the optical axis)between the surfaces of the second negative meniscus lens from theobject side within the 11 lens group and the cemented lens within the 11lens group, and f1 is the focal length of the first lens group.

Further, it is desirable for the following conditional formula to besatisfied within the range defined by Conditional Formula (3).

0.70<D4/f1<1.0  (3)′

In the case that the 11 lens group of the zoom lens of the presentinvention has the basic configuration described above, it is desirablefor following conditional formula to be satisfied:

−1.0<(R5−R7)/(R5+R7)<−0.1  (4)

wherein R5 is the radius of curvature of the surface of the cementedlens within the 11 lens group toward the object side, and R7 is theradius of curvature of the surface of the cemented lens within the 11lens group toward the image side.

Further, it is particularly desirable for the following conditionalformula to be satisfies within the range defined by Conditional Formula(4).

−0.8<(R5−R7)/(R5+R7)<−0.25  (4)′

In the case that the 11 lens group of the zoom lens of the presentinvention has the basic configuration described above, it is desirablefor following conditional formula to be satisfied:

20.0<νd2<35.0  (5)

wherein νd2 is the Abbe's number of the second negative meniscus lenswith respect to the d line.

Further, it is particularly desirable for the following conditionalformula to be satisfied within the range defined in Conditional Formula(5).

22.0<νd2<32.0  (5)′

In the case that the 11 lens group of the zoom lens of the presentinvention has the basic configuration described above, it is desirablefor following conditional formula to be satisfied:

35.0<νd4<100.0  (6)

wherein νd4 is the Abbe's number of the biconvex lens that forms thecemented lens within the 11 lens group with respect to the d line.

Further, it is particularly desirable for the following conditionalformula to be satisfied within the range defined in Conditional Formula(6).

40.0<νd4<72.0  (6)′

Still further, it is more particularly desirable for the followingconditional formula to be satisfied within the range defined inConditional Formula (6)′.

40.0<νd4<60.0  (6)″

Meanwhile, an imaging apparatus of the present invention ischaracterized by being equipped with the zoom lens of the presentinvention.

The zoom lens of the present invention is of the four groupconfiguration described above. The first lens group substantiallyconsists of: the 11 lens group having a negative refractive power whichis fixed during focusing operations; the 12 lens group having a positiverefractive power which moves during focusing operations; and the 13 lensgroup having the positive refractive power which is fixed duringfocusing operations, provided in this order from the magnification side.Therefore, variations in the angles of view during focusing operationscan be suppressed, as described in Japanese Patent Publication No.59(1984)-004686.

Further, in the zoom lens of the present invention, the 12 lens groupsubstantially consists of: the positive lens having a surface having aradius of curvature with a smaller absolute value toward the image side;and the cemented lens constituted by the negative lens toward the objectside and the positive lens toward the image side, cemented together at ajoint surface having a convex surface toward the object side, providedin this order from the magnification side. Therefore, it becomespossible to suppress variations in aberrations due to focusingoperations. Particularly by the joint surface being oriented asdescribed above, an advantageous effect, that variations in lateralchromatic aberration and astigmatism during focusing can be suppressed,becomes significant.

Further, the zoom lens of the present invention satisfies ConditionalFormula (1), and therefore the following advantageous effect can beobtained. That is, Conditional Formula (1) defines the ratio between thefocal length of the entire system at the wide angle end and the focallength of the 12 lens group. If the value of f12/fw is less than thelower limit defined in Conditional Formula (1), the refractive power ofthe 12 lens group will become excessively great, and the amount ofvariations in aberrations due to focusing operations will become great.Inversely, if the value of f12/fw is greater than the upper limitdefined in Conditional Formula (1), a large amount of space will becomenecessary to perform focusing operations from an infinitely far distanceto a close distance. In addition, the diameters of the lenses within the11 lens group and the 12 lens group will increase, resulting inreductions in size and weight becoming difficult. The above shortcomingscan be prevented in the case that Conditional Formula (1) is satisfied.If Conditional Formula (1) is satisfied, reductions in the size andweight of the zoom lens can be achieved, and variations in the amount ofaberrations due to focusing operations can be suppressed.

The advantageous effects described above will become more significant inthe case that Conditional Formula (1)′ is satisfied within the rangedefined in Conditional Formula (1).

In the case that the zoom lens of the present invention satisfiesConditional Formula (2), the following advantageous effects areobtained. That is, Conditional Formula (2) defines the ratio between thefocal distance of the entire system at the wide angle end and the focaldistance of the 11 lens group. If the value of f11/fw is less than thelower limit defined in Conditional Formula (2), a large amount of spacewill become necessary to perform focusing operations from an infinitelyfar distance to a close distance. In addition, the diameters of thelenses that constitute the 11 lens group and the 12 lens group willincrease, and it will become difficult to reduce the size and weight ofthe zoom lens. Inversely, if the value of f11/fw is greater than theupper limit defined in Conditional Formula (2), the refractive power ofthe 11 lens group will become excessively great, resulting in increasesin the amount of distortion at the wide angle end and the amount ofspherical aberration at the telephoto end. The above shortcomings can beprevented in the case that Conditional Formula (2) is satisfied. IfConditional Formula (2) is satisfied, reductions in the size and theweight of the zoom lens can be achieved, while the amount of distortionat the wide angle end and the amount of spherical aberration at thetelephoto end can be suppressed.

The advantageous effects described above will become more significant inthe case that Conditional Formula (2)′ is satisfied within the rangedefined in Conditional Formula (2).

In addition, in the case that the 11 lens group in zoom lens of thepresent invention has the basic configuration described above, thediameters of the lenses that constitute 11 lens group can be decreased,and high order spherical aberration at the telephoto end can besuppressed.

In the case that the 11 lens group in zoom lens of the present inventionhas the basic configuration described above and Conditional Formula (3)is satisfied, the following advantageous effects can be obtained. Thatis, Conditional Formula (3) defines the ratio between the focal distanceof the first lens group and the distance between the aforementionedsurfaces within the 11 lens group (the distance between the surfaces ofthe second negative meniscus lens from the object side and the cementedlens). If the value of D4/f1 is less than the lower limit defined inConditional Formula (3), field curvature will tend to be present towardthe lower side of images. If such field curvature is corrected by otherlens groups, high order field curvature will be generated, which isdifficult to correct. Inversely, if the value of D4/f1 is greater thanthe upper limit defined in Conditional Formula (3), field curvature willtend to be present toward the upper side of images. If such fieldcurvature is corrected by other lens groups, high order field curvaturewill be generated, which is difficult to correct. The above shortcomingscan be prevented if Conditional Formula (3) is satisfied, and it will bepossible to favorably correct field curvature.

The advantageous effect described above will become more significant inthe case that Conditional Formula (3)′ is satisfied within the rangedefined in Conditional Formula (3).

In the case that the 11 lens group in zoom lens of the present inventionhas the basic configuration described above and Conditional Formula (4)is satisfied, the following advantageous effects can be obtained. Thatis, Conditional Formula (4) defines the relationship between the radiusof curvature of the surface toward the object side and the surfacetoward the image side of the cemented lens within the 11 lens group. Ifthe value of (R5−R7)/(R5+R7) is less than the lower limit defined inConditional Formula (4), field curvature will tend to be present towardthe lower side of images, which is difficult to correct. Inversely, ifthe value of (R5−R7)/(R5+R7) is greater than the upper limit defined inConditional Formula (4), high order field curvature will be generated,which is difficult to correct. The above shortcomings can be preventedif Conditional Formula (4) is satisfied, and it will be possible tofavorably correct field curvature.

The advantageous effect described above will become more significant inthe case that Conditional Formula (4)′ is satisfied within the rangedefined in Conditional Formula (4).

In the case that the 11 lens group in zoom lens of the present inventionhas the basic configuration described above and Conditional Formula (5)is satisfied, the following advantageous effects can be obtained. Thatis, Conditional Formula (5) defines the Abbe's number of the secondnegative meniscus lens within the 11 lens group. If the value of νd2 isless than the lower limit defined in Conditional Formula (5), the amountof lateral chromatic aberration at the wide angle end becomes great.Inversely, if the value of νd2 is greater than the upper limit definedin Conditional Formula (5), the specific weight of the second negativemeniscus lens will become great, and the weight of the zoom lens willincrease. The above shortcomings can be prevented in the case thatConditional Formula (5) is satisfied, lateral chromatic aberration canbe suppressed at the wide angle end, and weight reduction of the zoomlens can also be realized. The second negative meniscus lens is a lenshaving a particularly large diameter within the entire system.Therefore, employing a glass material having a low specific weight isextremely advantageous from the viewpoint of weight reduction of thezoom lens.

The advantageous effects described above will become more significant inthe case that Conditional Formula (5)′ is satisfied within the rangedefined in Conditional Formula (5).

In the case that the 11 lens group in zoom lens of the present inventionhas the basic configuration described above and Conditional Formula (6)is satisfied, the following advantageous effects can be obtained. Thatis, Conditional Formula (6) defines the Abbe's number of the biconvexlens that constitutes the cemented lens within the 11 lens group. If thevalue of νd4 is less than the lower limit defined in Conditional Formula(6), the amount of lateral chromatic aberration will increase. If thislateral chromatic aberration is to be corrected by the other lensgroups, the Abbe's numbers of the other lenses, for example, the Abbe'snumber of the second negative meniscus lens, will increase, which willresult in glass materials having high specific weights being used,leading to an increase in the weight increase of the zoom lens.Inversely, if the value of νd4 is greater than the upper limit definedin Conditional Formula (6), the amount of lateral chromatic aberrationwill increase, and correction thereof will become difficult. The aboveshortcomings can be prevented if Conditional Formula (6) is satisfied,and weight reduction of the zoom lens can be realized while suppressingthe amount of lateral chromatic aberration.

The advantageous effects described above will become more significant inthe case that Conditional Formula (6)′ is satisfied, and further in thecase that Conditional Formula (6)″ is satisfied within the range definedin Conditional Formula (6).

Meanwhile, the imaging apparatus according to the present invention isequipped with the zoom lens of the present invention that exhibits theadvantageous effects described above. Therefore, the imaging apparatusof the present invention can prevent variations in the angle of viewduring focusing operations, suppress variations in various aberrationsduring focusing operations, is capable of imaging at high image quality,and can achieve reductions in size and weight.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a collection of diagrams that illustrate the lensconfiguration of a zoom lens according to Example 1 of the presentinvention.

FIG. 2 is a collection of diagrams that illustrate the lensconfiguration of a zoom lens according to Example 2 of the presentinvention.

FIG. 3 is a collection of diagrams that illustrate the lensconfiguration of a zoom lens according to Example 3 of the presentinvention.

FIG. 4 is a collection of diagrams that illustrate the lensconfiguration of a zoom lens according to Example 4 of the presentinvention.

FIG. 5 is a collection of diagrams that illustrate the lensconfiguration of a zoom lens according to Example 5 of the presentinvention.

FIG. 6 is a collection of diagrams that illustrate the lensconfiguration of a zoom lens according to Example 6 of the presentinvention.

FIG. 7 is a collection of diagrams that illustrate the lensconfiguration of a zoom lens according to Example 7 of the presentinvention.

FIG. 8 is a collection of diagrams that illustrate the lensconfiguration of a zoom lens according to Example 8 of the presentinvention.

FIG. 9 is a collection of diagrams that illustrate the lensconfiguration of a zoom lens according to Example 9 of the presentinvention.

A through H of FIG. 10 are diagrams that illustrate various aberrationsof the zoom lens according to Example 1 of the present invention.

A through H of FIG. 11 are diagrams that illustrate various aberrationsof the zoom lens according to Example 2 of the present invention.

A through H of FIG. 12 are diagrams that illustrate various aberrationsof the zoom lens according to Example 3 of the present invention.

A through H of FIG. 13 are diagrams that illustrate various aberrationsof the zoom lens according to Example 4 of the present invention.

A through H of FIG. 14 are diagrams that illustrate various aberrationsof the zoom lens according to Example 5 of the present invention.

A through H of FIG. 15 are diagrams that illustrate various aberrationsof the zoom lens according to Example 6 of the present invention.

A through H of FIG. 16 are diagrams that illustrate various aberrationsof the zoom lens according to Example 7 of the present invention.

A through H of FIG. 17 are diagrams that illustrate various aberrationsof the zoom lens according to Example 8 of the present invention.

A through H of FIG. 18 are diagrams that illustrate various aberrationsof the zoom lens according to Example 9 of the present invention.

FIG. 19 is a diagram that illustrates the schematic configuration of animaging apparatus according to an embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described indetail with reference to the attached drawings. FIG. 1 is a collectionof cross sectional diagrams that illustrate the configuration of a zoomlens according to an embodiment of the present invention, andcorresponds to a zoom lens of Example 1 to be described later. FIG. 2through FIG. 9 are collections of cross sectional diagrams thatillustrate configurations of zoom lenses according to other embodimentsof the present invention, and correspond to zoom lenses of Examples 2through 9 to be described later. The basic configurations of theembodiments illustrated in FIG. 1 through FIG. 9 are the same, and themanners in which the configurations are illustrated are also the same.Therefore, the zoom lenses according to the embodiments of the presentinvention will be described mainly with reference to FIG. 1.

In FIG. 1, the left side is the object side and the right side is theimage side. A of FIG. 1 illustrates the arrangement of the opticalsystem in a state focused on infinity at a wide angle end (shortestfocal length state). B of FIG. 1 illustrates the arrangement of theoptical system in a state focused on infinity at a telephoto end(longest focal length state). The same applies to FIGS. 2 through 9 tobe described later.

The zoom lens of the present embodiment consists of: a first lens groupG1 having a positive refractive power; a second lens group G2 having anegative refractive power; a third lens group having a negativerefractive power; and a fourth lens group G4 having a positiverefractive power, provided in this order from the object side.

The first lens group G1 consists of: an 11 lens group G11 having anegative refractive power, which is fixed during focusing operations; a12 lens group G12 having a positive refractive power, which moves duringfocusing operations; and a 13 lens group G13, which is fixed duringfocusing operations, provided in this order from the object side.

Note that the fourth lens group G4 includes an aperture stop St. Theaperture stop St illustrated in FIG. 1 does not necessarily representthe size or shape thereof, but only the position thereof on an opticalaxis Z. In addition, Sim illustrated in FIG. 1 is an imaging surface,and an imaging device, such as a CCD (Charge Coupled Device) and a CMOS(Complementary Metal Oxide Semiconductor), is provided at the imagingsurface, as will be described later.

Note that FIG. 1 illustrates an example in which a parallel plateoptical member PP is provided between the fourth lens group G4 and theimaging surface Sim. When the zoom lens is applied to an imagingapparatus, a cover glass and various filters, such as an infrared raycutoff filter and a low pass filter, are often provided between theoptical system and the imaging surface Sim, according to theconfiguration of a camera on which the lens is to be mounted. Theoptical member PP is provided assuming the presence of the cover glass,the various types of filters, and the like. In addition, recent imagingapparatuses employ the 3 CCD format, in which CCD's are employed foreach color in order to improve image quality. In order to be compatiblewith imaging apparatuses that employ the 3 CCD format, a colorseparating optical system such as a color separating prism may beinserted between the lens system and the imaging surface Sim. In thiscase, a color separating optical system may be provided at the positionof the optical member PP.

In the zoom lens of the present embodiment, the second lens group G2 andthe third lens group G3 move along the optical axis Z while changingmagnification. More specifically, while changing magnification from thewide angle end to the telephoto end, the second lens group G2 movestoward the imaging surface Sim along a curved path to changemagnification, and the third lens group G3 similarly moves toward theimaging surface Sim along a curved path, to correct movement of theimaging surface while changing magnification. Accordingly, the distancebetween the second lens group G2 and the first lens group graduallybecomes greater, the distance between the third lens group G3 and thefourth lens group G4, changes, and the distance between the second lensgroup G2 and the third lens group G3 changes, while changingmagnification from the wide angle end to the telephoto end. Meanwhile,the first lens group G1 and the fourth lens group G4 are fixed whilechanging magnification.

Note that FIG. 1 schematically illustrates the paths of movement of thesecond lens group G2 and the third lens group G3 while changingmagnification from the wide angle end to the telephoto end with thearrows indicated in solid lines between A and B. However, the paths ofmovement of the lens groups are not limited to those illustrated inFIG. 1. The basic paths of movement of the second lens group G2 and thethird lens group G3 of the present embodiment are common among Examples1 through 9. Therefore, arrows indicating the paths of movement areomitted in FIGS. 2 through 9.

Hereinafter, the lenses that constitute each of the lens groups will bedescribed. The 11 lens group G11 is constituted by a first lens L1, asecond lens L2, a third lens L3, and a fourth lens L4, provided in thisorder from the magnification side. For example, the first lens L1 is anegative meniscus lens having a concave surface toward the image side(that is, the side toward the imaging surface Sim at the right side ofFIG. 1). The second lens L2 is similarly a negative meniscus lens havinga concave surface toward the image side. The third lens L3 is abiconcave lens, and the fourth lens L4 is a biconvex lens. Note that inthe example illustrated in FIG. 1, the third lens L3 and the fourth lensL4 are cemented together to form a cemented lens.

The 12 lens group G12 is constituted by a fifth lens L5, a sixth lensL6, and a seventh lens L7, in this order from the object side. Forexample, the fifth lens L5 is a biconvex lens, the sixth lens L6 is anegative meniscus lens having a concave surface toward the image side,and the seventh lens L7 is a biconvex lens. Note that in the exampleillustrated in FIG. 1, a positive lens, that is, the fifth lens L5having a positive refractive power, is provided such that the surfacethereof having a radius of curvature with a smaller absolute value istoward the image side. The sixth lens L6 and the seventh lens L7 arecemented together to constitute a cemented lens. Note that the jointsurface of the cemented lens has a convex surface toward the object side(the left side in FIG. 1).

The 13 lens group G13 is constituted by an eighth lens L8 and a ninthlens L9, provided in this order from the object side. For example, theeighth lens L8 is a positive meniscus lens having a convex surfacetoward the image side, and the ninth lens L9 is a positive meniscus lenshaving a convex surface toward the object side.

Meanwhile, the second lens group G2 is constituted by a tenth lens L10,an eleventh lens L11, and a twelfth lens L12, provided in this orderfrom the object side. For example, the tenth lens L10 is a negativemeniscus lens having a concave surface toward the image side, theeleventh lens L11 is a biconcave lens, and the twelfth lens L12 is apositive meniscus lens having a convex surface toward the object side.

The third lens group G3 is constituted by a single thirteenth lens L13.The thirteenth lens L13 is a negative meniscus lens having a concavesurface toward the object side, for example.

The fourth lens group G4 is constituted by the aperture stop St, afourteenth lens L14, a fifteenth lens L15, a sixteenth lens L16, aseventeenth lens L17, an eighteenth lens L18, a nineteenth lens L19, atwentieth lens L20, a twenty first lens L21, a twenty second lens L22, atwenty third lens L23, and a twenty fourth lens L24, provided in thisorder from the object side. For example, the fourteenth lens L14 is abiconvex lens, the fifteenth lens L15 is a positive meniscus lens havinga convex surface toward the object side, the sixteenth lens L16 is apositive meniscus lens having a convex surface toward the object side,the seventeenth lens L17 is a negative meniscus lens having a concavesurface toward the image side, the eighteenth lens L18 is a biconvexlens, the nineteenth lens L19 is a negative meniscus lens having aconcave surface toward the image side, the twentieth lens L20 is abiconvex lens, the twenty first lens L21 is a biconcave lens, the twentysecond lens L22 is a biconvex lens, the twenty third lens L23 is anegative meniscus lens having a concave surface toward the object side,and the twenty fourth lens L24 is a biconvex lens. Note that thefollowing lenses, that is, the sixteenth lens L16 and the seventeenthlens L17, the nineteenth lens L19 and the twenty lens L20, and thetwenty first lens L21 and the twenty second lens L22, are respectivelycemented to each other.

As described above, in the present zoom lens, the first lens group G1substantially consists of: the 11 lens group G11 having a negativerefractive power which is fixed during focusing operations; the 12 lensgroup G12 having a positive refractive power which moves during focusingoperations; and the 13 lens group G13 having the positive refractivepower which is fixed during focusing operations, provided in this orderfrom the magnification side. By adopting this configuration, variationsin the angles of view during focusing operations can be suppressed, asdescribed in Japanese Patent Publication No. 59(1984)-004686.

In addition, the 12 lens group G12 substantially consists of: the fifthlens L5, which is a positive lens having a surface having a radius ofcurvature with a smaller absolute value toward the image side; and thecemented lens constituted by the sixth lens L6 and the seventh lens L7,provided in this order from the magnification side. The joint surface ofthe cemented lens has a convex surface toward the object side.Variations in aberrations due to focusing operations can be suppressed,by the 12 lens group G12 having the configuration described above.Particularly, the advantageous effects of suppressing the amount oflateral chromatic aberrations and variations in astigmatism duringfocusing operations become more prominent, by orienting the jointsurface in the manner described above.

Further, the present zoom lens satisfies the following conditionalformula:

3.0<f12/fw<20.0  (1)

wherein f12 is the focal length of the 12 lens group G12, and fw is thefocal length of the entire system at the wide angle end.

Further, the present zoom lens satisfies the following conditionalformula to within the range defined by Conditional Formula (1).

4.0<f12/fw<10.0  (1)′

Note that examples of the numerical values of the present embodimentwill be described in a summarized manner with reference to Tables 1through 28 later. For example, the value of the focal distance fw of theentire system at the wide angle end in the zoom lens of Example 1 isshown in the “Wide Angle End” column for Item f in Table 2. In addition,the value of the focal distance fw of the entire system at the wideangle end in the zoom lens of Example 2 is shown in the “Wide Angle End”column for Item f in Table 5, and the same applies to the otherExamples. The values of “f12/fw” for each of the examples are shown inTable 28, as are the values corresponding to Conditional Formulae (2)through (6) to be described later.

The zoom lens of the present embodiment satisfies Conditional Formula(1), and therefore exhibits the following advantageous effects. That is,Conditional Formula (1) defines the ratio between the focal length ofthe entire system at the wide angle end and the focal length of the 12lens group G12. If the value of f12/fw is less than the lower limitdefined in Conditional Formula (1), the refractive power of the 12 lensgroup G12 will become excessively great, and the amount of variations inaberrations due to focusing operations will become great. Inversely, ifthe value of f12/fw is greater than the upper limit defined inConditional Formula (1), a large amount of space will become necessaryto perform focusing operations from an infinitely far distance to aclose distance. In addition, the diameters of the lenses within the 11lens group G11 and the 12 lens group G12 will increase, resulting inreductions in size and weight becoming difficult. The above shortcomingscan be prevented in the case that Conditional Formula (1) is satisfied.If Conditional Formula (1) is satisfied, reductions in the size andweight of the zoom lens can be achieved, and variations in the amount ofaberrations due to focusing operations can be suppressed.

The zoom lens of the present embodiment satisfies Conditional Formula(1)′ within the range defined in Conditional Formula (1). Therefore, theabove advantageous effects are exhibited more prominently.

In addition, the zoom lens of the present embodiment satisfies thefollowing conditional formula:

−5.0<f11/fw<−0.5  (2)

wherein f11 is the focal length of the 11 lens group G11, and fw is thefocal length of the entire system at the wide angle end.

Further, the zoom lens of the present embodiment satisfies the followingconditional formula within the range defined by Conditional Formula (2)(refer to Table 28).

−3.0<f11/fw<−1.2  (2)′

The zoom lens of the present embodiment satisfies Conditional Formula(2), and therefore exhibits the following advantageous effects. That is,Conditional Formula (2) defines the ratio between the focal distance ofthe entire system at the wide angle end and the focal distance of the 11lens group G11. If the value of f11/fw is less than the lower limitdefined in Conditional Formula (2), a large amount of space will becomenecessary to perform focusing operations from an infinitely far distanceto a close distance. In addition, the diameters of the lenses thatconstitute the 11 lens group G11 and the 12 lens group G12 willincrease, and it will become difficult to reduce the size and weight ofthe zoom lens. Inversely, if the value of f11/fw is greater than theupper limit defined in Conditional Formula (2), the refractive power ofthe 11 lens group G11 will become excessively great, resulting inincreases in the amount of distortion at the wide angle end and theamount of spherical aberration at the telephoto end. The aboveshortcomings can be prevented in the case that Conditional Formula (2)is satisfied. If Conditional Formula (2) is satisfied, reductions in thesize and the weight of the zoom lens can be achieved, while the amountof distortion at the wide angle end and the amount of sphericalaberration at the telephoto end can be suppressed.

The zoom lens of the present embodiment satisfies Conditional Formula(2)′ within the range defined in Conditional Formula (2). Therefore, theabove advantageous effects are exhibited more prominently.

Further, in the zoom lens of the present invention, the 11 lens groupG11 is constituted by: the negative meniscus lens (the first lens L1)having a concave surface toward the image side; the negative meniscuslens (the second lens L2) similarly having a concave surface toward theimage side; and the cemented lens constituted by the biconcave lens (thethird lens L3) toward the object side and the biconvex lens (the fourthlens L4) toward the image side, which are cemented together, provided inthis order from the object side. By adopting this basic configuration,it becomes possible to for the 11 lens group to be miniaturized, andalso for high order spherical aberrations to be suppressed at thetelephoto end.

In addition, the 11 lens group Gil of the zoom lens according to thepresent embodiment has the basic configuration described above, andsatisfies the following conditional formula:

0.60<D4/f1<2.0  (3)

wherein D4 is the distance between the surfaces of the second negativemeniscus lens (the second lens L2) and the cemented lens (the cementedlens constituted by the lens L3 and the lens L4), and f1 is the focallength of the first lens group G1. Note that the above distance betweensurfaces is a spatial distance along the optical axis. Further, thefollowing conditional formula is satisfied within the range defined byConditional Formula (3) (refer to Table 28).

0.70<D4/f1<1.0  (3)′

The zoom lens of the present embodiment satisfies Conditional Formula(3), and therefore exhibits the following advantageous effect. That is,Conditional Formula (3) defines the ratio between the focal distance ofthe first lens group G1 and the distance between the aforementionedsurfaces (the distance between the surfaces of the second negativemeniscus lens from the object side and the cemented lens). If the valueof D4/f1 is less than the lower limit defined in Conditional Formula(3), field curvature will tend to be present toward the lower side ofimages. If such field curvature is corrected by other lens groups, highorder field curvature will be generated, which is difficult to correct.Inversely, if the value of D4/f1 is greater than the upper limit definedin Conditional Formula (3), field curvature will tend to be presenttoward the upper side of images. If such field curvature is corrected byother lens groups, high order field curvature will be generated, whichis difficult to correct. The above shortcomings can be prevented ifConditional Formula (3) is satisfied, and it will be possible tofavorably correct field curvature.

The present zoom lens satisfies Conditional Formula (3)′ within therange defined in Conditional Formula (3). Therefore, the advantageouseffect described above is more prominently exhibited.

In addition, the 11 lens group G11 of the zoom lens according to thepresent embodiment has the basic configuration described above, andsatisfies the following conditional formula:

−1.0<(R5−R7)/(R5+R7)<−0.1  (4)

wherein R5 is the radius of curvature of the surface of the cementedlens constituted by the lenses L3 and L4 within the 11 lens group G11toward the object side, and R7 is the radius of curvature of the surfaceof the cemented lens toward the image side.

Further, the zoom lens of the present embodiment satisfies the followingconditional formula within the range defined by Conditional Formula (4)(refer to Table 28).

−0.8<(R5−R7)/(R5+R7)<−0.25  (4)′

The zoom lens of the present embodiment satisfies Conditional Formula(4) described above, and therefore the following advantageous effectsare exhibited. That is, Conditional Formula (4) defines the relationshipbetween the radius of curvature of the surface toward the object sideand the surface toward the image side of the cemented lens within the 11lens group. If the value of (R5−R7)/(R5+R7) is less than the lower limitdefined in Conditional Formula (4), field curvature will tend to bepresent toward the lower side of images, which is difficult to correct.Inversely, if the value of (R5−R7)/(R5+R7) is greater than the upperlimit defined in Conditional Formula (4), high order field curvaturewill be generated, which is difficult to correct. The above shortcomingscan be prevented if Conditional Formula (4) is satisfied, and it will bepossible to favorably correct field curvature.

The zoom lens of the present embodiment satisfies Conditional Formula(4)′ within the range defined in Conditional Formula (4). Therefore, theadvantageous effect described above is more prominently exhibited.

In addition, the 11 lens group G11 of the zoom lens according to thepresent embodiment has the basic configuration described above, andsatisfies the following conditional formula:

20.0<νd2<35.0  (5)

wherein νd2 is the Abbe's number of the second negative meniscus lensfrom the object side within the 11 lens group G11, that is, the secondlens L2, with respect to the d line.

Further, the zoom lens of the present embodiment satisfies the followingconditional formula to be satisfied within the range defined inConditional Formula (5) (refer to Table 28).

22.0<νd2<32.0  (5)′

The zoom lens of the present embodiment satisfies Conditional Formula(5), and therefore the following advantageous effects are exhibited.That is, if the value of νd2 is less than the lower limit defined inConditional Formula (5), the amount of lateral chromatic aberration atthe wide angle end becomes great. Inversely, if the value of νd2 isgreater than the upper limit defined in Conditional Formula (5), thespecific weight of the second lens L2 will become great, and the weightof the zoom lens will increase. The above shortcomings can be preventedin the case that Conditional Formula (5) is satisfied, lateral chromaticaberration can be suppressed at the wide angle end, and weight reductionof the zoom lens can also be realized. The second lens L2 is a lenshaving a particularly large diameter within the entire system.Therefore, employing a glass material having a low specific weight isextremely advantageous from the viewpoint of weight reduction of thezoom lens.

The zoom lens of the present embodiment satisfies Conditional Formula(5)′ within the range defined in Conditional Formula (5). Therefore, theabove advantageous effects are more prominently exhibited.

In addition, the 11 lens group G11 of the zoom lens according to thepresent embodiment has the basic configuration described above, andsatisfies the following conditional formula:

35.0<νd4<100.0  (6)

wherein νd4 is the Abbe's number of the biconvex lens that constitutesthe cemented lens within the 11 lens group G11, that is, the fourth lensL4, with respect to the d line.

Further, the zoom lens of the present embodiment satisfies the followingconditional formula within the range defined in Conditional Formula (6).

40.0<νd4<72.0  (6)′

Still further, the zoom lens of the present embodiment satisfies thefollowing conditional formula (refer to Table 28).

40.0<νd4<60.0  (6)″

The zoom lens of the present embodiment satisfies Conditional Formula(6), and therefore the following advantageous effects are exhibited.That is, if the value of νd4 is less than the lower limit defined inConditional Formula (6), the amount of lateral chromatic aberration willincrease. If this lateral chromatic aberration is to be corrected by theother lens groups, the Abbe's numbers of the other lenses, for example,the Abbe's number νd2 of the second lens L2, will increase, which willresult in glass materials having high specific weights being used,leading to an increase in the weight increase of the zoom lens.Inversely, if the value of νd4 is greater than the upper limit definedin Conditional Formula (6), the amount of lateral chromatic aberrationwill increase, and correction thereof will become difficult. The aboveshortcomings can be prevented if Conditional Formula (6) is satisfied,and weight reduction of the zoom lens can be realized while suppressingthe amount of lateral chromatic aberration.

The zoom lens of the present embodiment satisfies Conditional Formula(6)′ and further satisfies Conditional Formula (6)″, within the rangedefined in Conditional Formula (6). Therefore, the above advantageouseffects are more prominently exhibited.

Next, examples of numerical values of the embodiments of the zoom lensof the present invention will be described in particular detail.

Example 1

As described previously, the arrangements of the zoom lens of Example 1at the wide angle end and at the telephoto end are illustrated inFIG. 1. Note that detailed descriptions of the lens groups and each lensin the configuration of FIG. 1 have already been given, and thereforeredundant descriptions will be omitted below unless particularlynecessary.

Table 1 shows basic lens data of the zoom lens of Example 1. Table 1also shows data regarding the optical member PP. In Table 1, ith (i=1,2, 3, . . . ) lens surface numbers that sequentially increase from theobject side to the image side, with the lens surface at the most objectside designated as first, are shown in the column Si. The radii ofcurvature of ith surfaces are shown in the column Ri, and the distancesbetween an ith surface and an i+1st surface along the optical axis Z areshown in the column Di. The refractive indices of jth (j=1, 2, 3, . . .) optical elements from the object side to the image side with respectto the d line (wavelength: 587.6 nm), j being a number that increasessequentially with the optical element most toward the object sidedesignated as first, are shown in the column Ndj. The Abbe's numbers ofthe jth optical element with respect to the d line are shown in thecolumn νdj. Note that the aperture stop St is also included in the basiclens data, and the radius of curvature of the surface corresponding tothe aperture stop St is shown as “∞” (aperture stop).

The units of the radii of curvature R and the distances D betweenadjacent lens surfaces are mm. Table 1 shows numerical values which arerounded to a predetermined number of digits. The signs of the radii ofcurvature are positive in cases that the surface shape is convex towardthe object side, and negative in cases that the surface shape is convextoward the image side.

Among the distances D between adjacent lens surfaces, the distancebetween the first lens group G1 and the second lens group G2, thedistance between the second lens group G2 and the third lens group G3,and the distance between the third lens group G3 and the fourth lensgroup G4 are variable distances that change while changingmagnification. “Variable Distance 16”, “Variable Distance 22”, and“Variable Distance 24” are shown in the columns corresponding to thesedistances, by adding the surface number of the front side surface.

In the lens data of Table 1, surface numbers of aspherical surfaces aredenoted with the mark “*”, and numerical values that represent paraxialradii of curvature are shown as the radii of curvature of the asphericalsurfaces.

The foregoing applies to Tables 4, 7, 10, 13, 16, 19, 22, and 25 to bedescribed later.

Table 2 shows the focal length f of the entire system at the wide angleend and at the telephoto end when the zoom lens of Example 1 changesmagnification, and the values of the aforementioned Variable Distance16, Variable Distance 22, and Variable Distance 24. Table 2 also showsvalues of the back focus BF, the F number F No., and the full angle ofview 2ω of the zoom lens of Example 1. The unit of measurement oflengths is also mm in Table 2, and the unit of measurement of the fullangle of view 2ω is degrees (°). Table 2 shows numerical values whichare rounded off at a predetermined number of digits as well. As shown inTable 2, the zoom lens of the present example has a full angle of viewof 91.82° at the wide angle end, which is a sufficiently wide angle ofview.

The manner in which items are shown in Table 2 described above alsoapply to Tables 5, 8, 11, 14, 17, 20, 23, and 26 to be described later.Note that the zoom lenses of Examples 2 through 9 have full angles ofview within a range from 91.80° to 91.84° at the wide angle end, whichare sufficiently wide angles of view.

Table 3 shows aspherical surface data of the zoom lens of Example 1.Table 3 shows the surface numbers of aspherical surfaces and theaspherical surface coefficients related to each of the asphericalsurfaces. In the numerical values of the aspherical surface coefficientsof Table 3, “E-n (n: integer)” means “.10^(−n)”. Note that theaspherical surface coefficients are the values of the coefficients KAand Am (m=3, 4, 5, . . . , 20) in the aspherical surface formula below:

Zd=C·h ²/{1+(1−KA·C ² ·h ²)^(1/2) }+ΣAm·h ^(m)

wherein: Zd is the depth of the aspherical surface (the length of anormal line that extends from a point on the aspherical surface having aheight h to a plane perpendicular to the optical axis that contacts thepeak of the aspherical surface), h is the height (the distance from theoptical axis to the surface of the lens), C is the inverse of theparaxial radius of curvature, and KA and Am are aspherical surfacecoefficients (m=3, 4, 5, . . . , 20).

The manner in which items are shown in Table 3 described above alsoapply to Tables 6, 9, 12, 15, 18, 21, 24, and 27 to be described later.

In all of the tables below, mm is used as the units for lengths anddegrees (°) are used as units of angles. However, it is possible foroptical systems to be proportionately enlarged or proportionatelyreduced and utilized. Therefore, other appropriate units may be used.

TABLE 1 Example 1: Basic Lens Data Si Ri ndj νdj (Surface (Radius of Di(Refractive (Abbe's Number) Curvature) (Distance) Index) Number)  170.6894 2.500 1.77250 49.60  2 36.2044 14.942 *3 78.3014 3.000 1.7173629.52  4 31.8282 33.886  5 −37.1642 2.351 1.51742 52.43  6 79.121710.569 1.69680 55.53  7 −103.2282 1.007  8 710.7794 7.791 1.49700 81.54 9 −72.7024 0.153 10 119.9323 2.350 1.88300 40.76 11 53.1778 12.2861.49700 81.54 12 −125.7910 4.180 13 −11562.9370 4.509 1.49700 81.54 14−132.5599 0.150 15 132.0399 3.837 1.72916 54.68 16 214748.3648 VariableDistance 16 17 176.3697 1.200 1.72916 54.68 18 29.1778 5.022 19−217.7742 1.200 1.56907 71.30 20 60.7196 5.862 21 48.4550 3.309 1.7173629.52 22 351.0532 Variable Distance 22 23 −53.3473 1.200 1.49700 81.5424 −430.3779 Variable Distance 24 25 ∞ (Aperture Stop) 2.000 26 106.43592.947 1.81600 46.62 27 −275.7217 1.001 28 34.0947 4.163 1.84139 24.56 29106.1829 0.156 30 28.5710 6.768 1.43875 94.93 31 172434.0964 2.0001.88300 40.76 32 25.5769 14.617 33 18.8629 5.981 1.49700 81.54 34−105.5462 0.250 35 147.7496 1.202 1.84661 23.78 36 11.6822 8.200 1.6516058.55 37 −57.4503 0.602 38 −33.8318 1.370 1.88300 40.76 39 19.0289 9.0491.54814 45.79 40 −16.0911 0.365 41 −15.0638 1.248 1.83481 42.71 42−80.2654 1.644 43 57.4547 4.779 1.84661 23.78 44 −73.5517 0.000 45 ∞2.490 1.51632 64.00 46 ∞ 30.151 *Aspherical Surface

TABLE 2 Example 1: Data Related to Zoom Item (d line) Wide Angle EndTelephoto End Zoom Ratio 1.0 2.8 f′ 16.00 44.80 Bf′ 31.79 31.79 FNo.2.65 2.65 2ω[°] 91.82 37.85 Variable Distance 16 2.000 48.516 VariableDistance 22 34.613 5.453 Variable Distance 24 19.357 2.002

TABLE 3 Example 1: Aspherical Surface Coefficients Surface Number 3 KA1.000000E+00 A3 −8.207591E−06  A4 3.612926E−06 A5 −9.721934E−08  A63.980679E−09 A7 −2.732476E−11  A8 −6.666219E−13  A9 2.921671E−15 A102.334960E−16 A11 4.493755E−18 A12 6.893503E−20 A13 9.185959E−22 A141.129241E−23 A15 1.316193E−25 A16 1.470968E−27 A17 1.574483E−29 A181.586896E−31 A19 1.429637E−33 A20 9.519133E−36

Table 28 shows the values of Examples 1 through 9 corresponding toConditional Formulae (1) through (6), that is, the variable portions ofthe conditional formulae. The values shown in Table 28 are related tothe d line. As shown in Table 28, the zoom lens of Example 1 and thezoom lenses of Examples 2 through 9 to be described later satisfy all ofConditional Formulae (1) through (6), and further satisfy ConditionalFormulae (1)′ through (6)′ as well as (6)″ that define more preferableranges within Conditional Formulae (1) through (6). The advantageouseffects obtained by satisfying these conditional formulae are thosewhich were previously described in detail.

The spherical aberration, the Abbe's sine condition, the astigmaticaberration, and the distortion of the zoom lens of Example 1 whenfocused on infinity at the wide angle end are illustrated in A through Dof FIG. 10, respectively. The spherical aberration, the Abbe's sinecondition, the astigmatic aberration, and the distortion of the zoomlens of Example 1 when focused on infinity at the telephoto end areillustrated in E through H of FIG. 10, respectively. Each of thediagrams that illustrate the aberrations use the d line (wavelength:587.6 nm) as a standard. However, aberrations related to the C line(wavelength: 656.3 nm) and the F line (wavelength: 486.1 nm) are alsoshown in the diagrams that illustrate spherical aberration. In thediagrams that illustrate astigmatic aberrations, aberrations in thesagittal direction are indicated by solid lines denoted with the letter(S), while aberrations in the tangential direction are indicated bybroken lines denoted by the letter (T). In the diagrams that illustratespherical aberrations and Abbe's sine conditions, “Fno.” denotes Fvalues. In the other diagrams that illustrate the aberrations, ω denoteshalf angles of view.

The manner in which the aberrations are illustrated described above alsoapply to FIG. 11 through FIG. 18 to be referred to later.

Example 2

FIG. 2 illustrates the arrangements of lens groups of a zoom lensaccording to Example 2 at the wide angle end and at the telephoto end.The zoom lens of Example 2 has approximately the same configuration asthat of the zoom lens according to Example 1 described above. However,the zoom lens of Example 2 differs from the zoom lens of Example 1 infour points, that an eighth lens L8 of a 13 lens group G13 is aplanoconvex lens having a convex surface toward the image side, that aninth lens L9 of the 13 lens group G13 is a planoconvex lens having aconvex surface toward the object side, that a sixteenth lens L16 of afourth lens group G4 is a planoconvex lens having a convex surfacetoward the object side, and that a seventeenth lens L17 of the fourthlens group G4 is a planoconcave lens having a concave surface toward theimage side.

Note that the zoom lenses of Example 2 through 9 differ from the zoomlens of Example 1 in the same four points. Therefore, the abovedescription will not be repeated in the descriptions of Examples 2through 9.

Table 4 shows basic lens data of the zoom lens of Example 2. Table 5shows data related to zoom of the zoom lens of Example 2. Table 6 showsaspherical surface data of the zoom lens of Example 2. A through H ofFIG. 11 are diagrams that illustrate various aberrations of the zoomlens of Example 2.

TABLE 4 Example 2: Basic Lens Data Si Ri ndj νdj (Surface (Radius of Di(Refractive (Abbe's Number) Curvature) (Distance) Index) Number)  174.3554 2.500 1.77250 49.60  2 37.0736 9.050 *3 74.6705 3.000 1.7173629.52  4 32.4015 40.474  5 −39.3056 2.351 1.51742 52.43  6 79.498410.832 1.68976 55.87  7 −95.0396 1.000  8 942.4408 6.741 1.49700 81.54 9 −84.1340 0.153 10 143.5405 2.350 1.88300 40.76 11 54.9687 10.7151.49700 81.54 12 −208.1561 4.636 13 ∞ 5.479 1.49700 81.54 14 −90.58710.150 15 130.9116 3.895 1.72735 54.79 16 ∞ Variable Distance 16 17175.4952 1.200 1.72604 54.86 18 29.5678 5.094 19 −188.4508 1.200 1.5707161.97 20 62.4076 5.379 21 48.8963 3.485 1.73296 28.72 22 389.6690Variable Distance 22 23 −57.8876 1.200 1.49700 81.54 24 −674.9530Variable Distance 24 25 ∞ (Aperture Stop) 2.000 26 106.0772 2.9461.81600 46.62 27 −289.6274 1.001 28 34.3478 4.199 1.84139 24.56 29102.9588 0.156 30 28.5956 7.020 1.43875 94.93 31 ∞ 2.000 1.88300 40.7632 25.7137 14.356 33 18.8684 6.008 1.49700 81.54 34 −102.4860 0.250 35152.1469 1.202 1.84661 23.78 36 11.7487 8.124 1.65160 58.55 37 −57.72850.607 38 −33.8090 1.373 1.88300 40.76 39 19.2141 8.993 1.54814 45.79 40−16.1301 0.405 41 −14.9925 1.248 1.83481 42.71 42 −85.8896 1.744 4363.9904 4.694 1.84661 23.78 44 −62.5397 0.000 45 ∞ 2.490 1.51632 64.0046 ∞ 30.164 *Aspherical Surface

TABLE 5 Example 2: Data Related to Zoom Item (d line) Wide Angle EndTelephoto End Zoom Ratio 1.0 2.8 f′ 16.00 44.81 Bf′ 31.81 31.81 FNo.2.64 2.64 2ω[°] 91.80 37.83 Variable Distance 16 2.000 49.972 VariableDistance 22 35.468 5.587 Variable Distance 24 20.060 1.969

TABLE 6 Example 2: Aspherical Surface Coefficients Surface Number 3 KA1.000000E+00 A3 −9.549332E−06  A4 3.435302E−06 A5 −1.009670E−07  A63.938844E−09 A7 −2.766388E−11  A8 −6.688923E−13  A9 2.909841E−15 A102.334913E−16 A11 4.495057E−18 A12 6.896460E−20 A13 9.190880E−22 A141.129956E−23 A15 1.317149E−25 A16 1.472178E−27 A17 1.575950E−29 A181.588620E−31 A19 1.431612E−33 A20 9.541324E−36

Example 3

FIG. 3 illustrates the arrangements of lens groups of a zoom lensaccording to Example 3 at the wide angle end and at the telephoto end.

Table 7 shows basic lens data of the zoom lens of Example 3. Table 8shows data related to zoom of the zoom lens of Example 3. Table 9 showsaspherical surface data of the zoom lens of Example 3. A through H ofFIG. 12 are diagrams that illustrate various aberrations of the zoomlens of Example 3.

TABLE 7 Example 3: Basic Lens Data Si Ri ndj νdj (Surface (Radius of Di(Refractive (Abbe's Number) Curvature) (Distance) Index) Number)  172.2277 2.500 1.77250 49.60  2 36.0856 14.893 *3 80.4940 3.000 1.7173629.52  4 32.6052 34.044  5 −37.4714 2.351 1.51742 52.43  6 75.677012.586 1.65858 57.45  7 −72.7386 1.000  8 773.9693 6.164 1.49700 81.54 9 −98.1399 0.153 10 123.0122 2.350 1.88300 40.76 11 55.0010 10.3981.49700 81.54 12 −275.3506 4.967 13 ∞ 5.551 1.49700 81.54 14 −89.86650.150 15 139.9896 3.845 1.70856 55.73 16 ∞ Variable Distance 16 17162.7064 1.200 1.73953 53.71 18 29.3009 5.205 19 −228.9447 1.200 1.5737856.13 20 64.0582 5.055 21 47.8155 3.362 1.75181 27.76 22 299.6376Variable Distance 22 23 −53.8761 1.200 1.49700 81.54 24 −599.1561Variable Distance 24 25 ∞ (Aperture Stop) 2.000 26 106.3867 2.9491.81600 46.62 27 −289.6165 1.001 28 34.1659 4.164 1.84139 24.56 29104.3918 0.156 30 28.3734 6.969 1.43875 94.93 31 ∞ 2.000 1.88300 40.7632 25.5927 14.474 33 18.8530 5.958 1.49700 81.54 34 −103.8817 0.250 35151.7393 1.202 1.84661 23.78 36 11.6858 8.194 1.65160 58.55 37 −57.53610.606 38 −33.7794 1.371 1.88300 40.76 39 18.9622 9.054 1.54814 45.79 40−16.1173 0.392 41 −15.0152 1.248 1.83481 42.71 42 −80.4952 1.617 4357.7359 4.667 1.84661 23.78 44 −70.2305 0.000 45 ∞ 2.490 1.51632 64.0046 ∞ 30.213 *Aspherical Surface

TABLE 8 Example 3: Data Related to Zoom Item (d line) Wide Angle EndTelephoto End Zoom Ratio 1.0 2.8 f′ 16.00 44.81 Bf′ 31.86 31.86 FNo.2.65 2.65 2ω[°] 91.83 37.85 Variable Distance 16 2.000 50.595 VariableDistance 22 36.156 5.352 Variable Distance 24 19.759 1.968

TABLE 9 Example 3: Aspherical Surface Coefficients Surface Number 3 KA1.000000E+00 A3 −8.057230E−06  A4 3.581432E−06 A5 −9.816251E−08  A63.963765E−09 A7 −2.754498E−11  A8 −6.689182E−13  A9 2.902062E−15 A102.333707E−16 A11 4.493514E−18 A12 6.894495E−20 A13 9.188327E−22 A141.129623E−23 A15 1.316721E−25 A16 1.471641E−27 A17 1.575295E−29 A181.587841E−31 A19 1.430705E−33 A20 9.530987E−36

Example 4

FIG. 4 illustrates the arrangements of lens groups of a zoom lensaccording to Example 4 at the wide angle end and at the telephoto end.

Table 10 shows basic lens data of the zoom lens of Example 4. Table 11shows data related to zoom of the zoom lens of Example 4. Table 12 showsaspherical surface data of the zoom lens of Example 4. A through H ofFIG. 13 are diagrams that illustrate various aberrations of the zoomlens of Example 4.

TABLE 10 Example 4: Basic Lens Data Si Ri ndj νdj (Surface (Radius of Di(Refractive (Abbe's Number) Curvature) (Distance) Index) Number)  169.7272 2.500 1.77250 49.60  2 36.2998 14.981 *3 76.8466 3.000 1.7173629.52  4 31.7073 33.857  5 −38.6477 2.351 1.51404 53.01  6 72.4553 9.9191.71676 54.52  7 −133.1199 1.075  8 956.5654 7.074 1.49700 81.54  9−76.3360 0.153 10 146.1610 2.350 1.88300 40.76 11 54.7391 10.998 1.4970081.54 12 −176.7059 3.847 13 ∞ 5.584 1.49700 81.54 14 −89.4220 0.150 15118.1062 4.258 1.74359 53.31 16 ∞ Variable Distance 16 17 165.3946 1.2001.73735 53.93 18 29.5050 5.192 19 −218.2346 1.200 1.57313 58.75 2064.7617 5.630 21 49.3403 3.279 1.74373 28.17 22 320.7702 VariableDistance 22 23 −54.0614 1.200 1.49700 81.54 24 −443.2194 VariableDistance 24 25 ∞ (Aperture Stop) 2.000 26 107.0968 2.976 1.81600 46.6227 −272.9713 1.001 28 34.2014 4.177 1.84139 24.56 29 103.6967 0.156 3028.7651 7.086 1.43875 94.93 31 ∞ 2.000 1.88300 40.76 32 25.5778 14.26133 18.8999 5.963 1.49700 81.54 34 −104.3511 0.250 35 147.3058 1.2021.84661 23.78 36 11.7114 8.208 1.65160 58.55 37 −57.4107 0.600 38−33.8701 1.371 1.88300 40.76 39 19.1249 9.018 1.54814 45.79 40 −16.11470.375 41 −15.0564 1.247 1.83481 42.71 42 −81.5615 1.596 43 58.2406 4.5131.84661 23.78 44 −72.0276 0.000 45 ∞ 2.490 1.51632 64.00 46 ∞ 30.483*Aspherical Surface

TABLE 11 Example 4: Data Related to Zoom Item (d line) Wide Angle EndTelephoto End Zoom Ratio 1.0 2.8 f′ 16.00 44.81 Bf′ 32.13 32.13 FNo.2.64 2.64 2ω[°] 91.83 37.83 Variable Distance 16 2.000 51.275 VariableDistance 22 37.840 5.187 Variable Distance 24 18.590 1.968

TABLE 12 Example 4: Aspherical Surface Coefficients Surface Number 3 KA1.000000E+00 A3 −8.722002E−06  A4 3.661445E−06 A5 −9.859539E−08  A63.955822E−09 A7 −2.754342E−11  A8 −6.677827E−13  A9 2.919501E−15 A102.335228E−16 A11 4.493999E−18 A12 6.893300E−20 A13 9.185005E−22 A141.129051E−23 A15 1.315898E−25 A16 1.470564E−27 A17 1.573970E−29 A181.586279E−31 A19 1.428919E−33 A20 9.511023E−36

Example 5

FIG. 5 illustrates the arrangements of lens groups of a zoom lensaccording to Example 5 at the wide angle end and at the telephoto end.

Table 13 shows basic lens data of the zoom lens of Example 5. Table 14shows data related to zoom of the zoom lens of Example 5. Table 15 showsaspherical surface data of the zoom lens of Example 4. A through H ofFIG. 14 are diagrams that illustrate various aberrations of the zoomlens of Example 5.

TABLE 13 Example 5: Basic Lens Data Si Ri ndj νdj (Surface (Radius of Di(Refractive (Abbe's Number) Curvature) (Distance) Index) Number)  164.6230 2.500 1.78974 49.03  2 35.3715 14.598 *3 83.2567 3.000 1.7173629.52  4 31.6880 34.190  5 −37.0492 2.351 1.55688 47.99  6 69.7934 8.5581.66978 46.74  7 −200.7063 1.000  8 493.2329 9.053 1.49700 81.54  9−57.9945 0.153 10 136.6891 2.350 1.88300 40.76 11 57.6224 11.609 1.4970081.54 12 −131.4761 2.749 13 ∞ 5.166 1.49700 81.54 14 −107.1222 0.150 15120.3617 4.332 1.74734 53.27 16 ∞ Variable Distance 16 17 200.7794 1.2001.73843 54.16 18 29.9830 5.170 19 −307.2689 1.201 1.57401 62.15 2077.8391 3.840 21 46.4870 3.528 1.72840 28.64 22 277.7492 VariableDistance 22 23 −54.8659 1.200 1.49700 81.54 24 −505.0282 VariableDistance 24 25 ∞ (Aperture Stop) 2.000 26 106.9126 3.037 1.81600 46.6227 −348.1424 1.001 28 34.6856 4.252 1.84139 24.56 29 99.4484 0.156 3029.5599 8.298 1.43875 94.93 31 ∞ 2.000 1.88300 40.76 32 25.5481 12.81633 18.9466 5.927 1.49700 81.54 34 −105.9301 0.250 35 142.0797 1.2021.84661 23.78 36 11.7515 8.194 1.65160 58.55 37 −54.2362 0.543 38−34.0434 1.369 1.88300 40.76 39 19.1526 9.023 1.54814 45.79 40 −16.08590.360 41 −15.0703 1.247 1.83481 42.71 42 −83.5461 1.441 43 57.5525 4.2661.84661 23.78 44 −76.0426 0.000 45 ∞ 2.490 1.51632 64.00 46 ∞ 31.101*Aspherical Surface

TABLE 14 Example 5: Data Related to Zoom Item (d line) Wide Angle EndTelephoto End Zoom Ratio 1.0 2.8 f′ 16.00 44.81 Bf′ 32.74 32.74 FNo.2.65 2.65 2ω[°] 91.82 37.82 Variable Distance 16 2.000 53.479 VariableDistance 22 35.918 5.751 Variable Distance 24 23.272 1.960

TABLE 15 Example 5: Aspherical Surface Coefficients Surface Number 3 KA1.000000E+00 A3 −8.028537E−06  A4 3.858002E−06 A5 −9.982085E−08  A63.904131E−09 A7 −2.815188E−11  A8 −6.710508E−13  A9 2.936930E−15 A102.342559E−16 A11 4.506490E−18 A12 6.910065E−20 A13 9.205020E−22 A141.131281E−23 A15 1.318271E−25 A16 1.473011E−27 A17 1.576436E−29 A181.588721E−31 A19 1.431308E−33 A20 9.534153E−36

Example 6

FIG. 6 illustrates the arrangements of lens groups of a zoom lensaccording to Example 6 at the wide angle end and at the telephoto end.

Table 16 shows basic lens data of the zoom lens of Example 6. Table 17shows data related to zoom of the zoom lens of Example 6. Table 18 showsaspherical surface data of the zoom lens of Example 6. A through H ofFIG. 15 are diagrams that illustrate various aberrations of the zoomlens of Example 6.

TABLE 16 Example 6: Basic Lens Data Si Ri ndj νdj (Surface (Radius of Di(Refractive (Abbe's Number) Curvature) (Distance) Index) Number)  170.1642 2.500 1.80010 39.22  2 35.9681 12.868 *3 71.0371 3.000 1.8000125.00  4 32.6673 34.625  5 −38.2698 2.351 1.49185 59.35  6 75.232111.649 1.66340 58.27  7 −93.5909 1.000  8 885.2254 6.700 1.49700 81.54 9 −87.7161 0.153 10 132.8142 2.350 1.88300 40.76 11 54.7989 10.8641.49700 81.54 12 −222.9344 4.489 13 ∞ 5.643 1.49700 81.54 14 −89.20750.150 15 133.5956 3.901 1.72916 54.68 16 ∞ Variable Distance 16 17168.7916 1.200 1.72296 55.35 18 29.7188 5.366 19 −207.9603 1.200 1.5492358.07 20 62.1428 5.395 21 48.6967 3.341 1.75072 27.90 22 292.6162Variable Distance 22 23 −53.0416 1.200 1.49700 81.54 24 −647.6773Variable Distance 24 25 ∞ (Aperture Stop) 2.000 26 104.5142 3.0131.81600 46.62 27 −272.8281 1.001 28 34.1968 4.185 1.84139 24.56 29107.0891 0.156 30 28.7635 6.472 1.43875 94.93 31 ∞ 2.000 1.88300 40.7632 25.6580 15.770 33 18.8143 6.186 1.49700 81.54 34 −106.5262 0.250 35146.0161 1.202 1.84661 23.78 36 11.7041 8.201 1.65160 58.55 37 −55.93700.579 38 −33.8350 1.369 1.88300 40.76 39 19.9998 8.831 1.54814 45.79 40−16.1330 0.392 41 −15.0283 1.248 1.83481 42.71 42 −80.4046 1.451 4356.7494 4.424 1.84661 23.78 44 −84.8917 0.000 45 ∞ 2.490 1.51632 64.0046 ∞ 29.754 *Aspherical Surface

TABLE 17 Example 6: Data Related to Zoom Item (d line) Wide Angle EndTelephoto End Zoom Ratio 1.0 2.8 f′ 16.01 44.82 Bf′ 31.40 31.40 FNo.2.64 2.64 2ω[°] 91.84 37.84 Variable Distance 16 2.000 51.576 VariableDistance 22 37.803 5.067 Variable Distance 24 19.340 2.500

TABLE 18 Example 6: Aspherical Surface Coefficients Surface Number 3 KA1.000000E+00 A3 −9.478749E−06  A4 3.429214E−06 A5 −9.984211E−08  A63.963807E−09 A7 −2.730521E−11  A8 −6.647467E−13  A9 2.951160E−15 A102.338501E−16 A11 4.497629E−18 A12 6.897615E−20 A13 9.190300E−22 A141.129701E−23 A15 1.316682E−25 A16 1.471491E−27 A17 1.575040E−29 A181.587489E−31 A19 1.430265E−33 A20 9.525775E−36

Example 7

FIG. 7 illustrates the arrangements of lens groups of a zoom lensaccording to Example 7 at the wide angle end and at the telephoto end.

Table 19 shows basic lens data of the zoom lens of Example 7. Table 20shows data related to zoom of the zoom lens of Example 7. Table 21 showsaspherical surface data of the zoom lens of Example 7. A through H ofFIG. 16 are diagrams that illustrate various aberrations of the zoomlens of Example 7.

TABLE 19 Example 7: Basic Lens Data Si Ri ndj νdj (Surface (Radius of Di(Refractive (Abbe's Number) Curvature) (Distance) Index) Number)  170.0579 2.500 1.77219 49.41  2 36.2423 10.214 *3 76.5478 3.000 1.7016429.92  4 32.8322 36.894  5 −37.8913 2.351 1.50613 54.82  6 67.098212.438 1.59432 61.37  7 −84.2919 1.001  8 673.8583 7.169 1.49700 81.54 9 −81.8695 0.153 10 130.3846 2.350 1.88300 40.76 11 56.9430 10.7191.49700 81.54 12 −242.0473 4.447 13 ∞ 5.734 1.49700 81.54 14 −90.32350.150 15 138.1575 3.878 1.72795 55.08 16 ∞ Variable Distance 16 17164.9341 1.200 1.71879 55.27 18 29.5396 5.314 19 −192.7389 1.200 1.5694448.61 20 59.8216 5.443 21 49.1912 3.338 1.76866 26.77 22 309.5695Variable Distance 22 23 −53.7796 1.200 1.49700 81.54 24 −547.9610Variable Distance 24 25 ∞ (Aperture Stop) 2.000 26 107.1775 3.0721.81600 46.62 27 −273.1519 1.001 28 34.2168 4.178 1.84139 24.56 29104.0250 0.156 30 28.5169 7.004 1.43875 94.93 31 ∞ 2.000 1.88300 40.7632 25.5786 14.155 33 18.8788 6.007 1.49700 81.54 34 −104.2122 0.250 35152.0637 1.202 1.84661 23.78 36 11.7126 8.178 1.65160 58.55 37 −58.04720.602 38 −34.0208 1.371 1.88300 40.76 39 19.0287 9.060 1.54814 45.79 40−16.0721 0.375 41 −15.0221 1.248 1.83481 42.71 42 −82.2867 1.602 4359.6133 4.769 1.84661 23.78 44 −67.4261 0.000 45 ∞ 2.490 1.51632 64.0046 ∞ 30.260 *Aspherical Surface

TABLE 20 Example 7: Data Related to Zoom Item (d line) Wide Angle EndTelephoto End Zoom Ratio 1.0 2.8 f′ 16.00 44.81 Bf′ 31.90 31.90 FNo.2.65 2.65 2ω[°] 91.82 37.84 Variable Distance 16 2.000 50.066 VariableDistance 22 36.097 5.333 Variable Distance 24 19.861 2.559

TABLE 21 Example 7: Aspherical Surface Coefficients Surface Number 3 KA1.000000E+00 A3 −9.583171E−06  A4 3.495978E−06 A5 −1.000529E−07  A63.946026E−09 A7 −2.761119E−11  A8 −6.682743E−13  A9 2.918938E−15 A102.336117E−16 A11 4.496398E−18 A12 6.897694E−20 A13 9.191739E−22 A141.129979E−23 A15 1.317087E−25 A16 1.472014E−27 A17 1.575672E−29 A181.588220E−31 A19 1.431085E−33 A20 9.534770E−36

Example 8

FIG. 8 illustrates the arrangements of lens groups of a zoom lensaccording to Example 8 at the wide angle end and at the telephoto end.

Table 22 shows basic lens data of the zoom lens of Example 8. Table 23shows data related to zoom of the zoom lens of Example 8. Table 24 showsaspherical surface data of the zoom lens of Example 8. A through H ofFIG. 17 are diagrams that illustrate various aberrations of the zoomlens of Example 8.

TABLE 22 Example 8: Basic Lens Data Si Ri ndj νdj (Surface (Radius of Di(Refractive (Abbe's Number) Curvature) (Distance) Index) Number)  168.9604 2.500 1.77251 49.01  2 35.9797 9.830 *3 75.1989 3.000 1.7053131.24  4 32.6579 37.081  5 −38.9664 2.351 1.57624 40.71  6 66.935612.394 1.66582 42.75  7 −83.9221 1.001  8 682.4675 7.130 1.49700 81.54 9 −81.8401 0.153 10 131.5226 2.350 1.88300 40.76 11 57.0713 10.3381.49700 81.54 12 −243.6474 4.376 13 ∞ 5.538 1.49700 81.54 14 −90.27040.150 15 136.2595 3.811 1.72849 55.08 16 ∞ Variable Distance 16 17169.8939 1.200 1.70180 56.41 18 29.6420 5.377 19 −186.4588 1.200 1.5541254.54 20 60.3951 5.637 21 49.4416 3.268 1.75285 27.79 22 289.5730Variable Distance 22 23 −55.0677 1.200 1.49700 81.54 24 −543.0122Variable Distance 24 25 ∞ (Aperture Stop) 2.000 26 107.7427 3.0771.81600 46.62 27 −273.5605 1.001 28 34.1779 4.178 1.84139 24.56 29104.1767 0.156 30 28.5567 6.967 1.43875 94.93 31 ∞ 2.000 1.88300 40.7632 25.6116 14.181 33 18.8878 5.956 1.49700 81.54 34 −103.1436 0.250 35151.0467 1.202 1.84661 23.78 36 11.7253 8.140 1.65160 58.55 37 −58.23640.607 38 −33.9810 1.371 1.88300 40.76 39 19.0361 9.050 1.54814 45.79 40−16.0831 0.383 41 −15.0113 1.248 1.83481 42.71 42 −83.3657 1.672 4360.1489 4.942 1.84661 23.78 44 −65.9877 0.000 45 ∞ 2.490 1.51632 64.0046 ∞ 30.104 *Aspherical Surface

TABLE 23 Example 8: Data Related to Zoom Item (d line) Wide Angle EndTelephoto End Zoom Ratio 1.0 2.8 f′ 16.00 44.81 Bf′ 31.75 31.75 FNo.2.65 2.65 2ω[°] 91.82 37.85 Variable Distance 16 2.000 51.054 VariableDistance 22 37.271 5.271 Variable Distance 24 19.018 1.963

TABLE 24 Example 8: Aspherical Surface Coefficients Surface Number 3 KA1.000000E+00 A3 −9.409151E−06  A4 3.493448E−06 A5 −1.001181E−07  A63.943622E−09 A7 −2.765256E−11  A8 −6.687414E−13  A9 2.914733E−15 A102.335778E−16 A11 4.496133E−18 A12 6.897478E−20 A13 9.191543E−22 A141.129959E−23 A15 1.317065E−25 A16 1.471988E−27 A17 1.575642E−29 A181.588185E−31 A19 1.431045E−33 A20 9.534323E−36

Example 9

FIG. 9 illustrates the arrangements of lens groups of a zoom lensaccording to Example 9 at the wide angle end and at the telephoto end.

Table 25 shows basic lens data of the zoom lens of Example 9. Table 26shows data related to zoom of the zoom lens of Example 9. Table 27 showsaspherical surface data of the zoom lens of Example 9. A through H ofFIG. 18 are diagrams that illustrate various aberrations of the zoomlens of Example 9.

TABLE 25 Example 9: Basic Lens Data Si Ri ndj νdj (Surface (Radius of Di(Refractive (Abbe's Number) Curvature) (Distance) Index) Number)  171.9586 2.500 1.77250 49.60  2 36.1245 14.901 *3 78.0794 3.000 1.7173629.52  4 32.3222 33.592  5 −38.2381 2.351 1.51742 52.43  6 75.040011.387 1.69680 55.53  7 −92.3604 1.000  8 908.8838 6.613 1.49700 81.54 9 −87.2167 0.153 10 133.8313 2.350 1.88300 40.76 11 54.6580 10.7281.49700 81.54 12 −227.7102 4.515 13 ∞ 5.539 1.49700 81.54 14 −90.27330.150 15 127.1125 4.023 1.72916 54.68 16 ∞ Variable Distance 16 17152.3952 1.200 1.72916 54.68 18 29.4212 5.255 19 −224.4541 1.200 1.5690771.30 20 62.5176 5.928 21 48.8107 3.279 1.71736 29.52 22 309.7564Variable Distance 22 23 −53.0405 1.200 1.49700 81.54 24 −398.1257Variable Distance 24 25 ∞ (Aperture Stop) 2.000 26 107.0313 2.9441.81600 46.62 27 −284.4562 1.001 28 34.1526 4.161 1.84139 24.56 29104.9592 0.156 30 28.5818 7.037 1.43875 94.93 31 ∞ 2.000 1.88300 40.7632 25.5163 14.145 33 18.8760 5.972 1.49700 81.54 34 −103.8754 0.250 35151.3530 1.202 1.84661 23.78 36 11.6950 8.166 1.65160 58.55 37 −58.59580.613 38 −33.9526 1.371 1.88300 40.76 39 18.9300 9.074 1.54814 45.79 40−16.0865 0.374 41 −15.0366 1.248 1.83481 42.71 42 −80.5008 1.494 4358.5774 4.455 1.84661 23.78 44 −69.0070 0.000 45 ∞ 2.490 1.51632 64.0046 ∞ 30.822 *Aspherical Surface

TABLE 26 Example 9: Data Related to Zoom Item (d line) Wide Angle EndTelephoto End Zoom Ratio 1.0 2.8 f′ 16.00 44.81 Bf′ 32.46 32.46 FNo.2.64 2.64 2ω[°] 91.84 37.84 Variable Distance 16 2.005 51.009 VariableDistance 22 37.567 5.193 Variable Distance 24 18.618 1.989

TABLE 27 Example 9: Aspherical Surface Coefficients Surface Number 3 KA1.000000E+00 A3 −8.344591E−06  A4 3.617715E−06 A5 −9.829526E−08  A63.965605E−09 A7 −2.745813E−11  A8 −6.677557E−13  A9 2.911158E−15 A102.334014E−16 A11 4.493082E−18 A12 6.893333E−20 A13 9.186511E−22 A141.129386E−23 A15 1.316440E−25 A16 1.471324E−27 A17 1.574950E−29 A181.587474E−31 A19 1.430322E−33 A20 9.527025E−36

TABLE 28 Conditional Example Example Example Example Example ExampleExample Example Example Number Formula 1 2 3 4 5 6 7 8 9 (1) f12/fw5.503 7.901 8.158 7.139 4.874 7.789 7.098 7.146 7.880 (2) f11/fw −1.938−2.203 −2.329 −1.898 −1.410 −2.147 −2.103 −2.068 −2.149 (3) D4/f1 0.7630.898 0.748 0.732 0.745 0.746 0.808 0.799 0.727 (4) (R5 − R7)/R5 + R7)−0.471 −0.415 −0.320 −0.550 −0.688 −0.420 −0.380 −0.366 −0.414 (5) ν229.52 29.52 29.52 29.52 29.52 25.00 29.92 31.24 29.52 (6) ν4 55.53 55.8757.45 54.52 46.74 58.27 61.37 42.75 55.53

Note that FIG. 1 illustrates an example in which the optical member PPis provided between the lens system and the imaging surface.Alternatively, various filters such as low pass filters and filters thatcut off specific wavelength bands may be provided among each of thelenses. As a further alternative, coatings that have the same functionsas the various filters may be administered on the surfaces of thelenses.

Next, an imaging apparatus according to an embodiment of the presentinvention will be described. FIG. 19 is a diagram that schematicallyillustrates an imaging apparatus 10 according to the embodiment of thepresent invention that employs a zoom lens 1 according to an embodimentof the present invention. The imaging apparatus 10 may be a digitalcinema camera, a surveillance camera, a video camera, an electronicstill camera, or the like.

The imaging apparatus 10 illustrated in FIG. 19 is equipped with: thezoom lens 1; a filter 2 provided toward the image side of the zoom lens1, an imaging device 3 that captures images of subjects focused by thezoom lens 1; a signal processing section 4 that processes signals outputfrom the imaging device 3; a magnification control section 5 thatchanges the magnification of the zoom lens 1; and a focus controlsection 6 that performs focus adjustments. Note that lens groups areschematically illustrated in FIG. 19.

The zoom lens 1 consists of a first lens group G1 having a positiverefractive power which is fixed while changing magnification, a secondlens group G2 having a negative refractive power that moves whilechanging magnification, a third lens group G3 having a negativerefractive power that moves while changing magnification, and a fourthlens group G4 having a positive refractive power which is fixed whilechanging magnification, provided in this order from the object side,that is, the left side of FIG. 19.

In the zoom lens 1, the second lens group G2 moves along the opticalaxis Z from the object side to the image side while changingmagnification from the wide angle end to the telephoto end. The thirdlens group G3 also moves along the optical axis Z to correct movement ofthe imaging surface while changing magnification. The movements of thelens groups G2 and G3 are controlled by the magnification controlsection 5.

The first lens group G1 consists of an 11 lens group G11 having anegative refractive power which is fixed during focusing operations, a12 lens group G12 having a positive refractive power that moves duringfocusing operations, and a 13 lens group G13 having a positiverefractive power which is fixed during focusing operations, provided inthis order from the object side. Movement of the 12 lens group G12 iscontrolled by the focus control section 6.

The imaging device 3 captures an optical image formed by the zoom lens 1and outputs electrical signals. The imaging surface thereof is providedto match the imaging plane of the zoom lens 1. A CCD, a CMOS, or thelike may be employed as the imaging device 3.

The imaging apparatus 10 is equipped with the zoom lens 1 of the presentinvention. Therefore, variations in angles of view during focusingoperations can be prevented, variations in various aberrations duringfocusing operations can be suppressed, thereby enabling high qualityimaging, and reductions in size and weight can be achieved.

The present invention has been described with reference to theembodiments and Examples thereof. However, the present invention is notlimited to the embodiments and Examples described above, and variousmodifications are possible. For example, the values of the radii ofcurvature of each lens component, the distances among surfaces, therefractive indices, the Abbe's numbers, the aspherical surfacecoefficients, etc., are not limited to the numerical values indicated inconnection with the Examples, and may be other values.

What is claimed is:
 1. A zoom lens, substantially consisting of: a firstlens group having a positive refractive power, which is fixed whilechanging magnification; a second lens group having a negative refractivepower, which moves from an object side to an image side while changingmagnification from a wide angle end to a telephoto end; a third lensgroup having a negative refractive power, which corrects movement of animaging surface while changing magnification; and a fourth lens grouphaving a positive refractive power, which is fixed while changingmagnification, provided in this order from the object side; the firstlens group substantially consisting of: an 11 lens group having anegative refractive power, which is fixed during focusing operations; a12 lens group having a positive refractive power, which moves duringfocusing operations; and a 13 lens group having a positive refractivepower, which is fixed during focusing operations, provided in this orderfrom the object side; the 12 lens group substantially consisting of: apositive lens having a surface having a radius of curvature with asmaller absolute value toward the image side; and a cemented lensconstituted by a negative lens toward the object side and a positivelens toward the image side, cemented together at a joint surface havinga convex surface toward the object side, provided in this order from themagnification side; the 12 lens group satisfying the followingconditional formula:3.0<f12/fw<20.0  (1) wherein f12 is the focal length of the 12 lensgroup, and fw is the focal length of the entire system at the wide angleend.
 2. A zoom lens as defined in claim 1 that satisfies the followingconditional formula:4.0<f12/fw<10.0  (1)′
 3. A zoom lens as defined in claim 1 thatsatisfies the following conditional formula:−5.0<f11/fw<−0.5  (2) wherein f11 is the focal length of the 11 lensgroup, and fw is the focal length of the entire system at the wide angleend.
 4. A zoom lens as defined in claim 3 that satisfies the followingconditional formula:−3.0<f11/fw<−1.2  (2)′.
 5. A zoom lens as defined in claim 1, whereinthe 11 lens group substantially consists of: a negative meniscus lenshaving a concave surface toward the image side; a negative meniscus lenshaving a concave surface toward the image side; and a cemented lensconstituted by a biconcave lens toward the object side and a biconvexlens toward the image side, which are cemented together, provided inthis order from the object side.
 6. A zoom lens as defined in claim 5,wherein the second meniscus lens from the object side within the 11 lensgroup and the cemented lens within the 11 lens group satisfy thefollowing conditional formula:0.60<D4/f1<2.0  (3) wherein D4 is the distance between the surfaces ofthe second negative meniscus lens and the cemented lens, and f1 is thefocal length of the first lens group.
 7. A zoom lens as defined in claim6 that satisfies the following conditional formula:0.70<D4/f1<1.0  (3)′.
 8. A zoom lens as defined in claim 5, wherein thecemented lens within the 11 lens group satisfies the followingconditional formula:−1.0<(R5−R7)/(R5+R7)<−0.1  (4) wherein R5 is the radius of curvature ofthe surface of the cemented lens toward the object side, and R7 is theradius of curvature of the surface of the cemented lens toward the imageside.
 9. A zoom lens as defined in claim 8 that satisfies the followingconditional formula:−0.8<(R5−R7)/(R5+R7)<−0.25  (4)°.
 10. A zoom lens as defined in claim 5,wherein the second meniscus lens from the object side within the 11 lensgroup satisfies the following conditional formula:20.0<νd2<35.0  (5) wherein νd2 is the Abbe's number of the secondnegative meniscus lens with respect to the d line.
 11. A zoom lens asdefined in claim 10 that satisfies the following conditional formula:22.0<νd2<32.0  (5)′.
 12. A zoom lens as defined in claim 5, wherein thebiconvex lens that constitutes the cemented lens within the 11 lensgroup satisfies the following conditional formula:35.0<νd4<100.0  (6) wherein νd4 is the Abbe's number of the biconvexlens with respect to the d line.
 13. A zoom lens as defined in claim 12that satisfies the following conditional formula:40.0<νd4<72.0  (6)′.
 14. A zoom lens as defined in claim 13 thatsatisfies the following conditional formula:40.0<νd4<60.0  (6)″.
 15. An imaging apparatus comprising a zoom lens asdefined in claim 1.